Embedded information modulation and demodulation using spectrum control orthogonal filter banks

ABSTRACT

A method and apparatus for information embedding modulation and information extraction demodulation are presented which use analysis and/or synthesis filter banks. Spectral control of the form of the composite signals arising from the embedding of digital embedded information signals into digital host signals is provided. Various implementations, including cable head-end and user-end systems using such modulators are presented. One aspect of the modulator allows for reduced noise spillover into adjacent communication channels in a multi-channel communication system. In some implementations the analysis and the synthesis filter banks form perfect reconstruction filter sets. In other implementations, block transforms are used as the filter banks.

FIELD OF THE INVENTION

[0001] This invention relates to the field of communication.Specifically, the invention addresses the combination of a hostcommunication signal and an embedded signal to yield a composite signalby a modulator, and the extraction of embedded signals from compositesignals by a demodulator.

BACKGROUND

[0002] A variety of applications exist for providing data to a userthrough communication channels used for transmitting host signals, suchas television signals. For example, closed captioning and teletextsystems are employed to display textual data that are associated with atelevision program. Additional applications include sending telephony,Internet, video enhancement, video-on-demand, video-streaming, oraudio-streaming data over television communications channels. Hostcommunication channels include those associated with broadcast“over-the-air” from ground-based antennas, from satellites, and overcable networks.

[0003] Cable networks typically are referred to as having a “head end”from which the cable television signals are transmitted. Thecommunication channels through which the transmissions occur may includefiber optic cables and coaxial cables, as well as a variety of switches,relays, and other conventional network components. Public switchedtelephone networks (PSTNs) or other telephone networks may alsoconstitute, or be included in, the cable network. For the sake ofconvenience, these communication channels are referred to herein simplyas “cables.” The television signals are received at what are referred toherein as “user ends.” For example, a cable network customer receivestelevision (TV) signals at a user end, where the signals may be coupledto television receivers, video recorders, computers, and other devices.

[0004] A variety of sources of television signals may be coupled to thehead end for transmission of the television signals over a cablenetwork. These television signals may include, for example, variouscommercial or public broadcast signals. Television signals include bothvideo signals and audio signals, and may also include data signals. Thetelevision signals typically are multiplexed at the head end into whatis referred to herein as “head-end multiplexed signals,” meaning a groupof television signals assembled at various carrier frequencies across aband of frequencies. The organizational scheme according to which thesesignals are assembled at the head end is commonly referred to as a“cable plant.”

[0005] In addition to carrying digital television signals, a portion ofthe cable plant may be dedicated to carrying conventional data signalsfrom the head end to the user ends. In particular, an industry standardreferred to as the Data Over Cable Service Interface Specification(DOCSIS) provides that cable operators may select portions of the cableplant within this range for the transmission of data signals. These datasignals may include captioning, teletext, telephony, Internet,television-enhancement, video-on-demand, video-streaming,audio-streaming, or other types of data.

[0006] Several approaches are available for addressing the problem oflimited bandwidth or data capacity in a conventional multi-drop cableconfiguration. One approach is to reduce the number of homes in a cableneighborhood (or “node”). Alternatively, additional cable nodes may becreated, each associated with its own common cable. A disadvantage ofthis approach, however, is the significant additional expense to thecable company of providing the additional cable from the head end to theusers.

[0007] Other approaches to increasing data capacity are applicable notonly to cable systems, but also to other forms of televisionbroadcasting such as over-the-air or satellite broadcasting. A reason toapply these approaches in non-cable systems is to increase opportunitiesto provide a variety of data services.

[0008] One of these approaches is to replace one or more televisionsignals with data signals. For example, a cable operator could replacethe television signals transmitted over one or more of analog televisionchannels and/or over digital television channels with data only. Adisadvantage of this approach is that the elimination of televisionsignals typically reduces revenues and also reduces the attractivenessof the cable service to users because of the reduced choice oftelevision signals.

[0009] Another approach to increasing the capacity of cable networks, orof other television broadcasting systems, is to transmit the data withone or more analog television signals according to certain approvedconventional methods. In the United States, the Federal CommunicationsCommission (FCC) has approved the inclusion of data signals with analogtelevision signals according to certain methods in over-the-airtelevision broadcast transmissions. See “Digital Data TransmissionWithin the Video Portion of Television Broadcast Station Transmissions,”FCC Report and Order, MM docket No. 95-42 (approved Jun. 21, 1996;published Jun. 28, 1996). Even prior to that order, the FCC hadpermitted the transmission of “ancillary telecommunications services”within the Vertical Blanking Interval (VBI) of television broadcastsignals in the NTSC (National Television System Committee) standard usedin the United States and elsewhere. The VBI is a portion of the NTSCbroadcast television signal that has no viewable content, i.e., itcontains no video signal. The reason for creating this blank portion isto allow time for the electron gun of the television receiver's cathoderay tube to move from the bottom to the top of the screen after scanningan image across the screen.

[0010] The VBI has been used to transmit such data as closed captioningand HTML-formatted information. For example, using the Intercastprotocol developed by Intel Corporation in 1996, CNN broadcasts links toits Internet pages to provide additional information related to itstelevision programs.

[0011] The FCC order of June 1996 referred to above, permitsbroadcasters to transmit ancillary information using so-called“overscan” methods proposed, as well as “subvideo” methods. In theoverscan method, data replaces a portion of the video signal that is notnormally seen by television viewers. For example, a method proposed byYes! Entertainment uses the extreme left edge of the picture, and othermethods use the first line of active video (after the VBI) at the top ofthe picture. In many television receivers, these edges are blocked fromviewing by the television cabinet. Overscan systems are capable oftransmitting data at relatively low rates, on the order of 15 to 20kilobits per second.

[0012] The sub-video technique takes advantage of portions of the 6-MHzbandwidth of a television signal that are typically filtered out by atelevision receiver. In other words, these are “blank” frequencies.Because the blank frequencies typically are not used to transmit eitherthe video or audio portion of the television signal, data may beinserted into them without interfering with either the picture or soundpresented to the viewer. These techniques allow data rates on the orderof 300 to 500 kilobits per second. The restricted data rates are due tothe fact that the blank frequencies constitute a small portion of thefull 6-MHz bandwidth.

SUMMARY

[0013] Generally, various embodiments of the present invention aredirected to information embedding modulators and information extractiondemodulators. Communication systems and methods for modulating anddemodulating using orthogonal filter banks are also provided. Manyequivalents to the given embodiments exist and can be developed usingthe novel concepts presented herein.

[0014] In one embodiment, an information embedding modulator system forgenerating a composite signal from an embedded information signal and ahost signal, comprises: an analysis filter bank operating on the hostsignal, the analysis filter bank producing a plurality of analysisfilter branch output signals; an information embedder for embedding theembedded information signal into a selected analysis filter branchoutput signal; a synthesis filter bank producing a plurality ofsynthesis filter branch output signals; and a combiner for combining thesynthesis filter branch output signals; wherein the combiner yields acomposite signal comprising information from both the host signal andthe embedded information signal.

[0015] In another embodiment, a method for modulating a host signal withan embedded information signal, comprises: (a) passing the host signalthrough an analysis filter bank having a plurality of analysis filterbranches; (b) embedding the embedded information signal into a selectedfilter branch output signal of the analysis filter bank to produce acomposite branch signal; (c) passing the composite branch signal andoutputs from other analysis filter bank output branch signals through asynthesis filter bank having a plurality of synthesis filter branches;and (d) combining outputs of the synthesis filter bank branches using acombiner to produce a composite signal.

[0016] In yet another embodiment, a method for modulating a host signalwith an embedded information signal, comprises: (a) splitting the hostsignal into a plurality of filtered branch signals using an analysisfilter bank; (b) decimating the filtered signals from (a) usingdown-samplers placed in at least one of the filtered branches; (c)embedding an embedded information signal into at least one of thedecimated filtered signals from (b) using an information embedder,producing at least one decimated branch composite signal; (d)interpolating each of the signals from (b) and the decimated branchcomposite signals from (c) using up-samplers placed in each of thebranches containing the signals from (b) and (c); (e) filtering each ofthe interpolated signals from (d) using a synthesis filter bankcorresponding to that signal; and (f) combining outputs of each branchin (e) to produce a composite signal comprising elements of both thehost signal and the embedded information signal.

[0017] In another embodiment, a method for embedding an embeddedinformation signal into a host signal occupying a host signal channel,with reduced spillover of the embedded information signal into signalchannels adjacent to the host signal channel, comprising: splitting thehost communication channel into a plurality of components using ananalysis filter bank, the analysis filter bank having a plurality ofoutput branches; decimating the host signal component in at least one ofthe output branches to produce a decimated host signal; and embeddingthe information signal into the decimated host signal to produce adecimated composite signal containing the information signal and thedecimated host signal.

[0018] Another exemplary embodiment provides a cable head-end systemadapted for embedding an embedded information signal into a host signal,comprising: a broadcast signal receiver receiving at least one broadcastchannel; an information embedding modulator for generating a compositesignal from the at least one broadcast channel and an embeddedinformation signal, the modulator comprising: an analysis filter bankoperating on the host signal, the analysis filter bank having at leastan analysis high-pass filter branch and an analysis low-pass filterbranch; an information embedder for embedding the embedded informationsignal into a selected analysis filter branch output; a synthesis filterbank, having at least a synthesis high-pass filter branch and asynthesis low-pass filter branch; and an adder for adding outputs of thesynthesis filter branches, the adder yielding a composite signalcontaining information from both the host signal and the embeddedinformation signal; and a transmitter for transmitting the compositesignal to a user.

[0019] In another embodiment, an information embedding modulator systemfor embedding an embedded information signal into a host signal isprovided, comprising: an analysis filter bank operating on the hostsignal, the analysis filter bank having an analysis filter branch with acorresponding analysis filter branch output; an information embedder forembedding the embedded information signal into the analysis filterbranch output; a first combiner for subtracting the analysis filterbranch output from an output of the information embedder; a synthesisfilter bank, having an input from the output of the first combiner; anda second combiner for combining an output of the synthesis filter bankand the host signal, the second combiner yielding a composite signalcontaining information from both the host signal and the embeddedinformation signal.

[0020] One illustrative embodiment is directed to a method for embeddingan embedded information signal into a host signal occupying a hostsignal channel, with reduced spillover of the embedded informationsignal into signal channels adjacent to the host signal channel,comprising: splitting the host communication channel into a plurality ofcomponents using an analysis filter bank, said analysis filter bankhaving an analysis filter branch component; decimating the host signalcomponent in the analysis filter branch component to produce a decimatedfiltered host signal; and embedding the information signal into thedecimated filtered host signal to produce a decimated filtered compositesignal comprising the embedded information signal and the decimatedfiltered host signal.

[0021] Another embodiment is directed to an information extractingdemodulator system for extracting embedded information from a compositesignal, comprising: an analysis filter bank, operating on the compositesignal, the analysis filter bank having an analysis filter output; andan information extractor for extracting embedded information from theanalysis filter output.

[0022] Yet another embodiment describes a method for demodulating acomposite signal, comprising: (a) filtering the composite signal usingan analysis filter bank; (b) extracting embedded information from thecomposite signal to yield extracted information corresponding to theembedded information.

[0023] One embodiment further provides a communication system, fordelivering information from a head end to a user end, comprising: aninformation embedding modulator for embedding embedded information intoa host signal, the modulator comprising a modulator analysis filterbank, an information embedder, a synthesis filter bank, and a combinerfor providing a composite signal containing information from both thehost signal and the embedded information signal, and an informationextracting demodulator, the demodulator comprising a demodulatoranalysis filter bank receiving and filtering the composite signal, andan information extractor for extracting the embedded information.

[0024] In another illustrative embodiment, a method for communicatingbetween a cable head end and a user end with reduced spillover of anembedded information signal into signal channels adjacent to a hostsignal channel is given, comprising: embedding the embedded informationsignal into at least a portion of the host signal using an informationembedder, wherein the portion of the host signal has a bandwidth smallerthan the bandwidth of the host signal channel; modulating the hostsignal with the embedded information signal using an informationembedding modulator, producing a composite signal comprising informationfrom both the host signal and the embedded information signal;transmitting the composite signal over a communication channel to theuser end; receiving the composite signal at the user end; anddemodulating the composite signal using an information extractiondemodulator adapted for extracting the embedded information signal fromthe composite signal.

[0025] Many advantages can be achieved by practicing the presentinvention, as covered by the scope of the accompanying claims. Someadvantages of some embodiments include, not by way of limitation:increasing the communication rate between a head-end and a user-end of acommunication system; utilizing unused bandwidth in cable communicationsystems; delivering associated data and information to a user of acommunication channel; and increasing the amount of informationdelivered per unit time without undue noise spillover between adjacentcommunication channels. These aspects are only a partial list, not anexhaustive list, and may be provided by some or all embodiments, some ofwhich are described herein for illustrative purposes.

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Aspects of the present invention will be more clearly appreciatedfrom the following Detailed Description section when taken inconjunction with the accompanying drawings, in which like referencenumerals indicate like structures or method steps.

[0027]FIG. 1 is a high-level schematic diagram of an embodiment of aninformation embedding modulator.

[0028]FIG. 2 is a high-level schematic diagram of an embodiment of aninformation extracting demodulator.

[0029]FIG. 3 is a schematic diagram of another embodiment of aninformation embedding modulator, showing low and high pass filterbranches.

[0030]FIG. 4 is a schematic diagram of yet another embodiment of aninformation embedding modulator, using samplers.

[0031]FIG. 5 is a schematic diagram of an embodiment of an informationembedding modulator having multiple filter branches.

[0032]FIG. 6 is a schematic diagram of an embodiment of an informationembedding modulator using a block transform implementation and havingseveral branches.

[0033]FIG. 7 is a schematic diagram of an embodiment of an informationextracting demodulator using a block transform implementation.

[0034]FIG. 8 is a schematic diagram of an embodiment of a cable head endsystem comprising an information embedding modulator.

[0035]FIG. 9 is a schematic diagram of an embodiment of a cable head endsystem with a multiplexer.

[0036]FIG. 10 is a schematic diagram of an embodiment of a user endsystem, comprising an information extracting demodulator.

[0037]FIG. 11 is a schematic diagram of an embodiment of an informationembedding modulator using an inverter.

[0038]FIG. 12 is a schematic diagram of an embodiment of an informationembedding modulator using inverters, multiple branches and blocktransforms.

[0039]FIG. 13 is an illustrative flow diagram showing a method forinformation embedding in an information embedding modulator.

[0040]FIG. 14 is an illustrative flow diagram showing a method forinformation extraction in an information extracting demodulator.

[0041]FIG. 15 is a diagram showing a signal level of an embeddedinformation signal relative to a noise floor and showing a guard band.

[0042]FIG. 16 shows the relative bandwidth of an embedded informationsignal, a television channel, and the guard bands.

DETAILED DESCRIPTION

[0043] In some aspects the present invention is described in the contextof cable networks and television signal transmissions. However, theinvention is not so limited, and may be implemented in connection withany other type of system used for broadcasting or otherwise deliveringor receiving communication signals, including over-the-air and ontelevision, radio, satellite, or telephone systems, as well as datatransmissions on the Internet, including over streaming media.

[0044] Reference is now made to FIG. 1, which shows an embodiment of aninformation embedding modulator 200. In general, a host signal 106 whichmay comprise audio, video, data, or other information in a variety offorms, is used as a signal into which an embedded information signal110, which can also consist of a variety of formats, is to be embedded.The information embedding modulator 200 generally comprises an analysisfilter bank 210, an information embedder 220, and a synthesis filterbank 230. The information embedding modulator 200 outputs a compositesignal 120, which comprises information from the original host signal106, as well as from the embedded information signal 110.

[0045] Some types of information embedder 220 designs which may be usedin the context of the present invention include non-intersectingembedding generators, distortion-compensated and non-compensated QIMmodulators, low-bit modulation, and spread-spectrum modulation systems.Examples of some of these designs are provided in thepreviously-disclosed U.S. patent application Ser. No. 09/616,299, and inU.S. patent application Ser. No. 09/616,705, which are herebyincorporated by reference.

[0046] In some embodiments, the analysis and the synthesis filter banksmay be related by their designs. For example, the synthesis filter bank230 might complement the corresponding analysis filter bank 210 suchthat the two filter banks form a perfect reconstruction filter set. Ofcourse, the invention is not limited to such arrangements, and otherembodiments may utilize other pairing schemes or none at all.

[0047] It should be understood that the terms “filter” and “filterbank”, as used herein, are also meant to include equivalents thereto.For example, certain block transforms are equivalent to filter banks,and the use of the term filter banks is meant to encompass suchequivalent transforms. The mathematical equivalence between filter banksand block transforms is thus relied on for certain implementations ofthe present invention. Specifically, in one embodiment, an extendedlapped transform (ELT), and a corresponding inverse ELT (I-ELT), areused to implement an orthogonal perfect reconstruction filter bank.

[0048] A “perfect reconstruction” filter bank set is defined in theliterature known to those skilled in the art. As used herein, a perfectreconstruction filter bank set is generally one where a multiple (e.g.,two) step filtering process results in an output signal which is thesame as that input to the filter bank set. For example, if a signal x isinput to an analysis filter bank, followed by a matched synthesis filterbank, then x will be output by the analysis-synthesis filter bank set ifthey are a perfect reconstruction filter bank set. In other words, thesynthesis filtering operation is an inverse of the analysis filteringoperation.

[0049] By “orthogonal” is meant a filter or transform where the basicfunctions are orthogonal as the term is known in the art, and the innerproduct of any two such basis functions is zero. The basic functions fora filter bank having multiple (M) branches are the impulse responses ofthe filter branches and shifts of these impulse responses by integermultiples of M.

[0050] An ELT may be used to decompose a host signal 106 into subbands,each of which may occupy an output branch of the ELT and contain aseparate frequency range. Different components of the same embeddedinformation signal 110 may be alternatively embedded into varioussubbands. Alternatively, entirely different signals may be embedded intothe different subbands.

[0051] Some aspects of the present invention take advantage of thecomputational efficiency of the ELT implementation in some embodiments.However, the invention is not so limited, and other implementations offilter banks are also understood to fall within its scope. Lappedtransform implementations can be considered special cases of multirateor polyphase implementations of the filter banks. The invention is meantto encompass by its scope all equivalent implementations, includingthose known to practitioners in the field and implementations discoveredin the future that could be employed for equivalent ends. Additionally,the decimation and interpolation filters used herein may be substitutedby corresponding polyphase implementations of these filters. Lappedtransform and other transforms including decimated uniform DFT banks aresubstantially equivalent to the filter banks referred to herein.

[0052] Next, we refer to FIG. 2 of the accompanying drawings. In orderto demodulate the composite signal 120 sent from the head end, aninformation extracting demodulator 201 is used at the user end of thecable, which is capable of extracting the extracted information signal110 a from the composite signal 120 a. The extracted information signal110 a is generally, but not necessarily, identical to the originalembedded information signal 110.

[0053] In general, the information extracting demodulator 201 operatesin a way that is complementary to the operation of the informationembedding modulator 200. Once the extracted information signal 110 a isextracted from the composite signal 120 a, the host signal 106 a may ormay not be used for any other purpose. That is, the host signal 106 amay be used at the user end for the information content within the hostsignal 106 a itself, or the host signal 106 a may have merely been usedas a carrier for the extracted information signal 110 a. Hence, thedemodulation process may terminate, in some embodiments, following theextraction of the extracted information signal 110 a, in which case thedesign of the demodulator 201 does not necessarily call for a synthesisfilter bank 230 a section, as used in the modulator 200.

[0054] In FIG. 2, a block diagram of a demodulator 201 is shownaccording to an embodiment of the present invention. The demodulator 201may correspond to one, for example, for use at the user end of a cablesystem having an information embedding modulator 200, as in FIG. 11 atthe head end. A composite signal 120 a is received at the user end. Thecomposite signal 120 a contains information from the original hostsignal 106 as well as from the embedded information signal 110, asdescribed earlier. The composite signal 120 a is passed through ananalysis filter bank 210 a, which corresponds to an analysis filter bank210 of the embedding modulator 200.

[0055] The analysis filter bank 210 a may be identical to filter bank210, or may correspond to analysis filter bank 210 in some other way.For example, the demodulator's analysis filter bank 210 a may beimplemented using an ELT transform implementation, as described above,while the corresponding analysis filter bank 210 of the modulator isimplemented directly as filters in software and/or hardware. Othersuitable implementations are of course possible, and include withoutlimitation, all of the filter and transform embodiments described hereinand in the art of the instant field.

[0056] After passing through the analysis filter bank 210 a, the signalis sent to an information extractor 221. The information extractor 221operates in a manner complementary to the operation of the informationembedder 220. Several forms may be taken in design of the informationextractor 221, akin to those described above and elsewhere, and in thereferences incorporated herein by reference, or otherwise known now orbecome known to those skilled in the art.

[0057] A more detailed schematic illustration of an informationembedding modulator system is provided in FIG. 3. In general, theanalysis filter bank 210 and the synthesis filter bank 230 may consistof a plurality of filter bank branches, 210 a-b and 230 a-brespectively. FIG. 3 shows an embodiment of the invention in which theanalysis and the synthesis filter banks have two branches each. Theanalysis filter bank 210 comprises an analysis high-pass filter branch210 a and an analysis low-pass filter branch 210 b. The output from theanalysis low-pass filter branch 210 b is then sent to the informationembedder 220, wherein the embedded information signal 110 is combinedwith the output of the analysis low-pass filter branch 210 b.

[0058] Both the output of the analysis high-pass filter branch 210 a andthe output of the information embedder 220 are passed onto the synthesisfilter bank 230. The synthesis filter bank comprises a synthesishigh-pass filter branch 230 a and a synthesis low-pass filter branch 230b. Additionally, the synthesis filter bank 230 in this embodimentcomprises a combiner 280. The combiner may take the form of an adder.

[0059] The output of the analysis high-pass filter branch 210 a is inputto the synthesis high-pass filter branch 230 a. The output of theinformation embedder 220 is input to the synthesis low-pass filterbranch 230 b. The outputs of the synthesis high-pass filter branch 230 aand the synthesis low-pass filter branch 230 b are then combined by thecombiner 280 to produce a composite signal 120.

[0060] Note that, in general, any branch or branches of the analysisfilter bank 210 can be used to output to the information embedder 220.Also note that the analysis filter 210 may consist of any number ofbranches, and that any one or more of these may be coupled to one ormore information embedders 220.

[0061] In some embodiments, the use of a down-sampler 250 and anup-sampler 260 may be advantageous. FIG. 4 shows an exemplary blockdiagram of a system using down-samplers and up-samplers. A host signal106 is input to an information embedding modulator 200 as before. Theoutputs from the analysis high-pass filter branch 210 a and the analysislow-pass filter branch 210 b are sent to at least one down-samplercomponent, for example 250 a, 250 b. The output of the high-pass filterbranch down-sampler 250 a is input to a corresponding up-sampler 260 ain the synthesis filter bank 230, and the output of the low-pass filterbranch down-sampler 250 b is input to the information embedder 220. Theoutput of the information embedder 220 is then input to the up-sampler260 b in the synthesis filter bank 230.

[0062] The up-samplers 260 a and 260 b then send their outputs to thesynthesis high-pass filter branch 230 a and the synthesis low-passfilter branch 230 b, respectively. The outputs of the synthesishigh-pass filter 230 a and the synthesis low-pass filter 230 b are thencombined by the combiner 280 to produce a digital composite signal 120as before. The combiner 280 may carry out an addition operation.

[0063] As mentioned earlier, some embodiments of the invention may begeneralized to filter banks having an arbitrary number of branches. Forexample, FIG. 5 shows an illustrative schematic diagram of an embodimentof the invention using M branches in each of the analysis filter bank210 and the synthesis filter bank 230. The host signal 106 is split intoM branches, each used by one branch of the analysis filter bank 210.Analysis filter branches, 210 a, 210 b, . . . 240M, yield outputs whichare sent to down-samplers 250 a, 250 b, . . . 250M. The output of thei^(th) down-sampler, 250 i,is sent to the information embedder 220,wherein the embedded information signal 110 is combined with the outputof the i^(th) down-sampler 250 i. More than one information embedder 220may be utilized in a single information embedding modulator system 200.Furthermore, the information embedder 220 may be placed in any branch ina multiple branch embedding modulator system, or in more than onebranch. Each output from the analysis filter bank 210 is then input asdescribed earlier to a corresponding input of the synthesis filter bank230, and the outputs of the synthesis filter branches 230 are thencombined in the combiner 280 to yield the composite signal 120.

[0064] An alternate embodiment of an information embedding modulator 200is shown in i. A host signal 106 is input to an extended lappedtransform 400, which has several branch outputs. The exemplaryembodiment shown in FIG. 6 has the embedded information signal 110 beingembedded using information embedders 220 into a plurality of outputbranches. Note that the embedded information signal 110 embedded by theinformation embedders 220 may be identical embedded information signals110 entering each branch of the ELT 400 output, or the embeddedinformation signals 110 entering each branch may be different componentsof a signal from which the components are derived. Alternatively,unrelated signals may be used for embedding into each of the branches.The plurality of information embedders 220 send their outputs to aninverse extended lapped transform (I-ELT) 410. The I-ELT 410 thenprovides a composite signal 120 containing both host signal 106information as well as any embedded information signal or signals 110.

[0065] An information extracting demodulator 201 corresponding, e.g., tothe information embedding modulator 200 of FIG. 6, is shown in FIG. 7.In this exemplary embodiment, a block transform equivalent of theanalysis filter is used. An ELT 400 a provides outputs to a plurality ofinformation extractors 221, from which extracted information signals 110a are obtained.

[0066]FIG. 8 shows an embodiment of a cable head end system 300,employing an information embedding modulator 200 to produce an analogcomposite signal 124 from a compound broadcast signal 100 and anembedded information signal 110. In this example, the compound broadcastsignal 100 is received by a compound broadcast signal receiver 275,which may be a satellite signal receiver or a television signal receiveror another type of receiver adapted for receiving analog broadcastsignals. The output of the compound broadcast signal receiver 275 issent to a down-converter 265. The down-converter 265 is adapted forfrequency conversion of the broadcast signals to a lower intermediatefrequency or to baseband. For example, a 44 MHz signal produced by thebroadcast signal receiver 275 may be down-converted to an intermediatefrequency of 6.5 MHz. The down-converted signal produced by thedown-converter 265 is then converted from an analog signal to a digitalsignal in an analog-to-digital converter (ADC) 295. The output of theADC 295 may then be used as a (digital) host signal 106 for hosting theembedded information signal 110 in the information embedding modulator200.

[0067] Once the information embedding process is performed by theinformation embedding modulator 200, and a composite signal 120 isoutput by the information embedding modulator 200, the composite signal120 is sent to a digital-to-analog converter (DAC) 290. The DAC 290 thensends an (analog) composite signal 120 to an up-converter 225. Theup-converter 225 then shifts the frequency of the analog compositesignal 120 back to broadcast frequencies, e.g., 50-550 MHz, or to anintermediate frequency, e.g., 44 MHz. The up-converted analog compositesignal 124 may then be sent out over a cable transmission line, nowcontaining embedded information, as well as original broadcast signalinformation.

[0068] It should be noted that the compound broadcast signal 100 mayexist in numerous forms. For example, satellite signals, televisionbroadcast signals, cellular communication signals, or other broadcastsignals which may be received by a receiver 275. In addition, thecompound broadcast signal 100 may comprise a plurality of channels thatare received and decoded by or in the vicinity of the receiver 275.

[0069] In one embodiment, shown in FIG. 9, one or more of the receivedchannels of the compound broadcast signal 100 may be used for thepurposes of the information embedding modulator 200, while the otherreceived channels may be sent to a multiplexer (MUX) 285, bypassing theinformation embedding modulator 200 and the information modulationprocess. In this case, the channels not used for information modulationmay be re-introduced into the cable for delivery to recipients of cablehead end services by use of a multiplexer 285 arranged to incorporatethe compound information coming from the information embeddingmodulation system as well as the channels not used for informationembedding.

[0070]FIG. 10 shows a block diagram of one embodiment of a user end 301incorporating an information extracting demodulator 201. According tothis exemplary embodiment, a multiplexed TV signal 331 is received by aTV tuner 332. The TV tuner 332 output is sent through an ADC 295 a, thenthe information extracting demodulator 201 extracts the extractedinformation signal 110 a.

[0071] In FIG. 11, yet another embodiment of an information embeddingmodulator 200 is shown, wherein one branch of the host signal 106bypasses the analysis filter bank 210 and is sent directly to a secondcombiner 284 to be combined with a composite branch signal. Thecomposite branch signal is obtained by passing the host signal 106through the analysis filter bank 210 as before, but an inverted, times(-1), tap is generated using the inverter 305 to produce a subtractedsignal for adding via the first combiner 282 to a branch that comes fromthe information embedder 220. The output of the second combiner 284 is acomposite signal 120. The second combiner 284 may be incorporated withinthe synthesis filter bank 230 in some embodiments, or may be implementedoutside the synthesis filter bank 230.

[0072] Another alternate embodiment of an information embeddingmodulator 200 is shown in FIG. 12 using a lapped transformimplementation. A host signal 106 is sent to an ELT 400 as well as to acombiner 280. The ELT 400 has a plurality of output branches, one,several, or all of which may be used to embed embedded informationsignals 110 using information embedders 220. The outputs from the ELT400 are sent to inverters 305 in each embedding branch, which arecombined in combiners 282 with the outputs of information embedders 220.ELT 400 output branches into which no information signal is to beembedded, are represented by zero out 420 to indicate that no embeddingand no inversion is to take place in those branches. The result of allof the combiner 282 outputs as well as the zero out 420 branches areinput to an I-ELT 410 whose output is combined with the original hostsignal 110 in the combiner 280 to provide the output composite signal120.

[0073]FIG. 13 shows an embodiment of a method for information embeddingusing an information embedding modulator, comprising:

[0074] a) Receiving a broadcast signal. The broadcast signal may be asingle channel or a group of channels, in digital or in analog format,as described earlier.

[0075] b) Processing the received broadcast signal, including an act ofselecting or extracting a host signal. The processing may comprise morethan one act, such as converting from one frequency to another, orconversion from an analog to a digital format, etc.

[0076] c) Filtering the host signal through an analysis filter bank, asdescribed earlier in this application.

[0077] d) Embedding an embedded information signal into the host signalusing an information embedder.

[0078] e) Filtering the host-plus embedded signal and the host signalbranch or branches through a synthesis filter bank as describedpreviously.

[0079] f) Combining the host signal branches with the host-plus embeddedsignal branch using a combiner. A plurality of host signal branches anda plurality of branches containing embedded information may be combinedby the combiner as described earlier.

[0080] Depending on the application and the format of the host signaland the desired composite signal, the act provided above may beperformed in conjunction with, or in addition to, other acts such asdown-converting a host broadcast signal, passing an analog channelthrough an analog-to-digital converter to obtain a digital host signal,passing the composite signal through a digital-to-analog converter toproduce an analog composite signal, and up-converting an analogcomposite signal using an up-converter.

[0081]FIG. 14 shows an embodiment of a method for extraction of embeddedinformation to yield an extracted information signal, comprising:

[0082] a) Receiving a composite signal.

[0083] b) Processing the composite signal, including by frequencyconversion or analog-to-digital conversion techniques as describedearlier.

[0084] c) Filtering the composite signal through an analysis filterbank.

[0085] d) Extracting embedded information using an information extractorto yield an extracted information signal.

[0086] Depending on the application and the format of the compositesignal and the desired extracted information signal, the acts above mayinclude or be performed in conjunction with other acts such as thosedescribed previously in this application.

[0087] The extracted information signal generally corresponds to apreviously embedded information signal, such as embedded informationsignal 110. The extracted information signal may, in fact, be identicalto the embedded information signal.

[0088] It should be understood that other auxiliary functions may beaccomplished in conjunction with those listed above. For example,frequency shifting or conversion, analog-to-digital anddigital-to-analog conversion, combining and splitting a signal withother signals such as by multiplexing and demultiplexing, as well asfunctions required or desired for reception and transmission of a signalor components thereof.

[0089] One aspect of the present invention allows for spectral controlin the overall cable transmission and in the signal channel transmissionin a multi-channel transmission cable. Since the effect of embeddingdata into a transmitted communication channel is to add a smallcontrollable amount of noise to the existing noise floor of the cableplant, there exists a risk of creating noise spillover into adjacentcommunication channels, thus degrading their transmission quality.Accordingly, in some embodiments of the present invention, thisspillover effect may be reduced or eliminated by providing a “guardband” 310 to separate the frequencies carrying the embedded informationfrom frequencies in which adjacent communication channel information iscarried. For example, by using a branch of the analysis filter bank asthe branch into which the embedded information is placed, it can bepossible by designing the filter banks according to some aspects of thepresent invention, to restrict the embedded information into a bandwidthB₂ narrower than the overall host signal bandwidth B₁. As an example,for a television-type host signal having a bandwidth B₁ of 6 MHz, theembedded information may be inserted into the bandwidth B₂ from 0 to4.75 MHz, depending on the application and the design of the analysisfilter bank 210. By so doing, a tail off or roll off buffer zone, alsoreferred to herein as the guard band 310, may protect adjacent channelsfrom spillover of noise from the embedded information signal.

[0090] By using more sophisticated analysis filter bank 210, theembedded information signal 110 spectrum may be shaped to suit thepurpose at hand. For example, the embedded information signal 110spectrum may be designed to account for the human visual perceptual orauditory models. Some advantages for spectrum control, according to someembodiments of the invention, include hiding embedded information, orminimizing the apparent effects of the embedded information on the hostsignal.

[0091] With reference to FIGS. 15 and 16, an illustrative example of theuse of spectrum control for reduced noise spillover is shown. In FIG.15, a plot of signal strength S(f) is shown as a function of frequencyf. The figure shows an embedded information signal 110 as a shadedregion, as well as a noise floor 320. The embedded information signal110 occupies a bandwidth B₂. This allows for a finite guard band 310having a bandwidth of (B₁-B₂), where B₁ is the bandwidth of a host TVchannel signal 330.

[0092]FIG. 16 shows the TV channel signal 330 occupying a bandwidth B₁centered on a frequency f₁. The embedded information signal 110 ofbandwidth B₂ is introduced into the TV channel 330 allowing for a guardband 310 on either side of the embedded information signal 110bandwidth. Also shown along the frequency axis is a greater bandwidthrepresenting the oversampling 340 associated with the TV channel signal330. It should be clear that, by proper selection of transmission andembedding bandwidths determined by the associated filter bank selection,appropriate guard bands 310 can be achieved.

[0093] While only certain preferred and exemplary features andembodiments of the invention have been illustrated and described herein,many modifications and changes will occur to those skilled in the art.It is, therefore, to be understood that the appended claims are intendedto cover any and all such modifications and changes as fall within therange of equivalence and in the spirit of the invention.

1. An information embedding modulator system for generating a compositesignal from an embedded information signal and a host signal,comprising: an analysis filter bank operating on the host signal, theanalysis filter bank producing a plurality of analysis filter branchoutput signals; an information embedder for embedding the embeddedinformation signal into a selected analysis filter branch output signal;a synthesis filter bank producing a plurality of synthesis filter branchoutput signals; and a combiner for combining the synthesis filter branchoutput signals; wherein the combiner yields a composite signalcomprising information from both the host signal and the embeddedinformation signal.
 2. The system of claim 1, wherein the analysisfilter bank comprises at least an analysis high-pass filter branch andan analysis low-pass filter branch.
 3. The system of claim 1, whereinthe synthesis filter bank comprises at least a synthesis high-passfilter branch and a synthesis low-pass filter branch.
 4. The system ofclaim 1, wherein the analysis filter bank comprises a polyphase filter.5. The system of claim 1, wherein the analysis filter bank comprises adecimated uniform discrete Fourier transform filter bank.
 6. The systemof claim 1, wherein the analysis filter bank comprises a blocktransformer.
 7. The system of claim 6, wherein the block transformer isadapted for performing an extended lapped transform.
 8. The system ofclaim 1, wherein the synthesis filter bank comprises a polyphase filter.9. The system of claim 1, wherein the synthesis filter bank comprises adecimated uniform discrete Fourier transform filter bank.
 10. The systemof claim 1, wherein the synthesis filter bank comprises a blocktransformer.
 11. The system of claim 10, wherein the block transformeris adapted for performing an inverse extended lapped transform.
 12. Thesystem of claim 1, wherein the information embedder comprises anon-intersecting embedding generator.
 13. The system of claim 1, whereinthe information embedder comprises a distortion-compensated QIMmodulator.
 14. The system of claim 1, wherein the information embeddercomprises a non-compensated QIM modulator.
 15. The system of claim 1,wherein the information embedder comprises a low-bit modulationembedder.
 16. The system of claim 1, wherein the information embeddercomprises a spread-spectrum modulation embedder.
 17. The system of claim1, wherein the combiner is included within the synthesis filter bank.18. The system of claim 1, wherein the combiner comprises an adder. 19.The system of claim 1, further comprising a down-sampler at an output ofan analysis filter branch.
 20. The system of claim 1, further comprisingan up-sampler at an input of a synthesis filter branch.
 21. The systemof claim 1, wherein the analysis filter bank and the synthesis filterbank form a perfect reconstruction filter set.
 22. The system of claim2, wherein the analysis high-pass filter and the analysis low-passfilter are orthogonal.
 23. The system of claim 1, further comprising abroadcast signal receiver for generating the host signal.
 24. The systemof claim 23, wherein the broadcast signal is a television signal. 25.The system of claim 24, wherein the television signal is of any of theformats: PAL, PAL-M, PAL-N, SECAM, MESECAM, and NTSC.
 26. The system ofclaim 1, further comprising a multiplexer for multiplexing the compositesignal and a second signal.
 27. The system of claim 1, furthercomprising an analog-to-digital converter at the input of theinformation embedding modulator.
 28. The system of claim 1, furthercomprising a multiplexer at the output of the information embeddingmodulator for inserting a composite signal into a multiplexed signal.29. The system of claim 1, further comprising a digital-to-analogconverter for converting a digital composite signal into an analogcomposite signal.
 30. The system of claim 1, wherein any of the filters,samplers, and information embedder are implemented using a digitalsignal processing technique.
 31. The system of claim 1, wherein any ofthe filters, samplers, and information embedder are implemented usingapplication specific integrated circuit hardware.
 32. The system ofclaim 1, wherein any of the filters, samplers, and information embedderare implemented using field programmable gate arrays.
 33. The system ofclaim 1, wherein any of the filters, samplers, and information embedderare implemented using a combination of hardware and software.
 34. Amethod for modulating a host signal with an embedded information signal,comprising: (a) passing the host signal through an analysis filter bankhaving a plurality of analysis filter branches; (b) embedding theembedded information signal into a selected filter branch output signalof the analysis filter bank to produce a composite branch signal; (c)passing the composite branch signal and outputs from other analysisfilter bank output branch signals through a synthesis filter bank havinga plurality of synthesis filter branches; (d) combining outputs of thesynthesis filter bank branches using a combiner to produce a compositesignal.
 35. The method of claim 34, wherein combining the outputs of thesynthesis filter bank branches using a combiner comprises adding theoutputs of the synthesis filter bank using an adder.
 36. The method ofclaim 34, further comprising converting an analog host signal into adigital host signal using an analog-to-digital converter.
 37. The methodof claim 34 further comprising converting the composite signal to ananalog composite signal using a digital-to-analog converter.
 38. Themethod of claim 34, further comprising multiplexing the composite signaland a second signal, generating a multiplexed signal.
 39. A method formodulating a host signal with an embedded information signal,comprising: (a) splitting the host signal into a plurality of filteredbranch signals using an analysis filter bank; (b) decimating thefiltered signals from (a) using down-samplers placed in at least one ofthe filtered branches; (c) embedding an embedded information signal intoat least one of the decimated filtered signals from (b) using aninformation embedder, producing at least one decimated branch compositesignal; (d) interpolating each of the signals from (b) and the decimatedbranch composite signals from (c) using up-samplers placed in each ofthe branches containing the signals from (b) and (c); (e) filtering eachof the interpolated signals from (d) using a synthesis filter bankcorresponding to that signal; (f) combining outputs of each branch in(e) to produce a composite signal comprising elements of both the hostsignal and the embedded information signal.
 40. The method of claim 39,wherein the synthesis filter bank and the analysis filter bank form aperfect reconstruction filter set.
 41. The method of claim 39, whereincombining outputs of each branch in (e) to produce a composite signalcomprises adding outputs of each branch in (e) to produce a compositesignal.
 42. A method for embedding an embedded information signal into ahost signal occupying a host signal channel, with reduced spillover ofthe embedded information signal into signal channels adjacent to thehost signal channel, comprising: splitting the host communicationchannel into a plurality of components using an analysis filter bank,the analysis filter bank having a plurality of output branches;decimating the host signal component in at least one of the outputbranches to produce a decimated host signal; embedding the informationsignal into the decimated host signal to produce a decimated compositesignal containing the information signal and the decimated host signal.43. The method of claim 42, further comprising oversampling andinterpolating the decimated composite signal.
 44. The method of claim42, further comprising oversampling and interpolating the decimated hostsignal.
 45. The method of claim 42, further comprising combining thedecimated composite signal from at least one of the output branches toproduce a combined composite signal containing host signal informationand embedded signal information.
 46. The method of claim 42, wherein thedecimating and filtering are carried out by a decimating analysis filterbank.
 47. The method of claim 42, wherein the oversampling andinterpolating are carried out by an interpolating reconstruction filterbank.
 48. The method of any of claims 42-43, wherein the filtering andinterpolating satisfy a Nyquist criterion to produce substantially zerointer-symbol interference.
 49. A cable head-end system adapted forembedding an embedded information signal into a host signal, comprising:a broadcast signal receiver receiving at least one broadcast channel; aninformation embedding modulator for generating a composite signal fromthe at least one broadcast channel and an embedded information signal,the modulator comprising: an analysis filter bank operating on the hostsignal, the analysis filter bank having at least an analysis high-passfilter branch and an analysis lowpass filter branch; an informationembedder for embedding the embedded information signal into a selectedanalysis filter branch output; a synthesis filter bank, having at leasta synthesis high-pass filter branch and a synthesis low-pass filterbranch; and an adder for adding outputs of the synthesis filterbranches, the adder yielding a composite signal containing informationfrom both the host signal and the embedded information signal; and atransmitter for transmitting the composite signal to a user.
 50. Thesystem of claim 49, further comprising a down-converter for converting afirst frequency to a second lower frequency.
 51. The system of claim 49,further comprising an up-converter for converting a first frequency to asecond higher frequency.
 52. The system of claim 49, further comprisingan analog-to-digital converter upstream of the information embeddingmodulator.
 53. The system of claim 49, further comprising adigital-to-analog converter downstream of the information embeddingmodulator.
 54. An information embedding modulator system for embeddingan embedded information signal into a host signal, comprising: ananalysis filter bank operating on the host signal, the analysis filterbank having an analysis filter branch with a corresponding analysisfilter branch output; an information embedder for embedding the embeddedinformation signal into the analysis filter branch output; a firstcombiner for subtracting the analysis filter branch output from anoutput of the information embedder; a synthesis filter bank, having aninput from the output of the first combiner; and a second combiner forcombining an output of the synthesis filter bank and the host signal,the second combiner yielding a composite signal containing informationfrom both the host signal and the embedded information signal.
 55. Thesystem of claim 54, wherein the first combiner comprises an adder. 56.The system of claim 54, wherein the first combiner comprises aninverter.
 57. The system of claim 54, further comprising an inverter atan input of the first combiner.
 58. The system of claim 54, wherein thesecond combiner is included within the synthesis filter bank.
 59. Thesystem of claim 54, further comprising a down-sampler at the output ofthe analysis filter branch.
 60. The system of claim 54, furthercomprising an up-sampler at the input of the synthesis filter branch.61. The system of claim 54, wherein the analysis filter bank and thesynthesis filter bank form a perfect reconstruction filter set.
 62. Thesystem of claim 54, further comprising a broadcast signal receiver forgenerating the host signal.
 63. The system of claim 62, wherein thebroadcast signal is a television signal.
 64. The system of claim 63,wherein the television signal is of any of the formats PAL, PAL-M,PAL-N, SECAM, MESECAM, and NTSC.
 65. The system of claim 54, furthercomprising an analog-to-digital converter placed at an input of theinformation embedding modulator system.
 66. The system of claim 54,further comprising a multiplexer at an output of the informationembedding modulator system for inserting a composite signal into amultiplexed signal.
 67. The system of claim 54, further comprising adigital-to-analog converter placed at an output of the informationembedding modulator system.
 68. The system of claim 54, wherein any ofthe filters, samplers, and information embedder are implemented using adigital signal processor.
 69. The system of claim 54, wherein any of thefilters, samplers, and information embedder are implemented usingapplication specific integrated circuit hardware.
 70. The system ofclaim 54, wherein any of the filters, samplers, and information embedderare implemented using field programmable gate arrays.
 71. The system ofclaim 54, wherein any of the filters, samplers, and information embedderare implemented using a combination of hardware and software.
 72. Thesystem of claim 54, wherein the analysis filter bank comprises at leastan analysis high-pass filter branch and an analysis low-pass filterbranch.
 73. The system of claim 54, wherein the synthesis filter bankcomprises at least a synthesis high-pass filter branch and a synthesislow-pass filter branch.
 74. The system of claim 54, wherein the analysisfilter bank comprises a polyphase filter.
 75. The system of claim 54,wherein the analysis filter bank comprises a block transformer.
 76. Thesystem of claim 75, wherein the block transformer comprises an extendedlapped transformer.
 77. The system of claim 54, wherein the synthesisfilter bank comprises a polyphase filter.
 78. The system of claim 54,wherein the synthesis filter bank comprises a block transformer.
 79. Thesystem of claim 78, wherein the block transformer comprises an inverseextended lapped transformer.
 80. The system of claim 54, wherein theinformation embedder comprises a non-intersecting embedding generator.81. The system of claim 54, wherein the information embedder comprises adistortion-compensated QIM modulator.
 82. The system of claim 54,wherein the information embedder comprises a non-compensated QIMmodulator.
 83. The system of claim 54, wherein the information embeddercomprises a low-bit modulation embedder.
 84. The system of claim 54,wherein the information embedder comprises a spread-spectrum modulationembedder.
 85. A method for embedding an embedded information signal intoa host signal occupying a host signal channel, with reduced spillover ofthe embedded information signal into signal channels adjacent to thehost signal channel, comprising: splitting the host communicationchannel into a plurality of components using an analysis filter bank,said analysis filter bank having an analysis filter branch component;decimating the host signal component in the analysis filter branchcomponent to produce a decimated filtered host signal; and embedding theinformation signal into the decimated filtered host signal to produce adecimated filtered composite signal comprising the embedded informationsignal and the decimated filtered host signal.
 86. The method of claim85, further comprising subtracting the decimated filtered host signalfrom the decimated filtered composite signal.
 87. The method of claim85, further comprising oversampling and interpolating the decimatedfiltered composite signal.
 88. The method of claim 85, furthercomprising combining the decimated filtered composite signal and thehost signal to produce a composite signal containing host signalinformation and embedded signal information.
 89. The method of claim 85,wherein the decimating and filtering are carried out in a decimatinganalysis filter bank.
 90. The method of claim 85, wherein theoversampling and interpolating are carried out in a synthesis filterbank.
 91. The method of claim 90, wherein the analysis and the synthesisform a perfect reconstruction operation.
 92. The method of claim 86,wherein the decimation and interpolation satisfy a Nyquist criterion toproduce substantially zero inter-symbol interference.
 93. An informationextracting demodulator system for extracting embedded information from acomposite signal, comprising: an analysis filter bank, operating on thecomposite signal, the analysis filter bank having an analysis filteroutput; and an information extractor for extracting embedded informationfrom the analysis filter output.
 94. The system of claim 93, wherein theanalysis filter bank comprises at least an analysis high-pass filterbranch and an analysis low-pass filter branch.
 95. The system of claim93, wherein the analysis filter bank comprises a polyphase filter. 96.The system of claim 93, wherein the analysis filter bank comprises ablock transformer.
 97. The system of claim 96, wherein the blocktransformer comprises an extended lapped transformer.
 98. The system ofclaim 93, further comprising a demultiplexer for demultiplexing thecomposite signal and a second signal.
 99. The system of claim 93,further comprising a down-sampler at an output of an analysis filterbranch.
 100. The system of claim 93, further comprising a receiver forreceiving the composite signal.
 101. The system of claim 93, wherein thecomposite signal comprises an embedded information and a host signalinformation.
 102. The system of claim 101, wherein the host signal is atelevision signal.
 103. The system of claim 102, wherein the televisionsignal is of any of the formats: PAL, PAL-M, PAL-N, SECAM, MESECAM, andNTSC.
 104. The system of claim 93, further comprising ananalog-to-digital converter for converting an analog composite signal toa digital composite signal.
 105. The system of claim 93, wherein any ofthe filters, samplers, and information extractor are implemented using adigital signal processing technique.
 106. The system of claim 93,wherein any of the filters, samplers, and information extractor areimplemented using application specific integrated circuit hardware. 107.The system of claim 93, wherein any of the filters, samplers, andinformation extractor are implemented using field programmable gatearrays.
 108. The system of claim 93, wherein any of the filters,samplers, and information extractor are implemented using a combinationof hardware and software.
 109. A method for demodulating a compositesignal, comprising: (a) filtering the composite signal using an analysisfilter bank; (b) extracting embedded information from the compositesignal to yield extracted information corresponding to the embeddedinformation.
 110. The method of claim 109, further comprisingdemultiplexing a multiplexed signal to obtain the composite signaltherefrom.
 111. A communication system, for delivering information froma head end to a user end, comprising: an information embedding modulatorfor embedding embedded information into a host signal, the modulatorcomprising a modulator analysis filter bank, an information embedder, asynthesis filter bank, and a combiner for providing a composite signalcontaining information from both the host signal and the embeddedinformation signal, and an information extracting demodulator, thedemodulator comprising a demodulator analysis filter bank receiving andfiltering the composite signal, and an information extractor forextracting the embedded information.
 112. The system of claim 111,wherein the modulator analysis filter and the demodulator analysisfilter have substantially similar transfer functions.
 113. The system ofclaim 111, wherein any of the filters is implemented as polyphasefilters.
 114. The system of claim 111, wherein any of the filters isimplemented as a block transform.
 115. The system of claim 114, whereinthe block transform comprises an extended lapped transform.
 116. Thesystem of claim 111, further comprising a broadcast signal receiver forreceiving a broadcast signal.
 117. The system of claim 111, furthercomprising a multiplexer for multiplexing a plurality of communicationchannels, at least one of which serves as a host channel.
 118. A methodfor communicating between a cable head end and a user end with reducedspillover of an embedded information signal into signal channelsadjacent to a host signal channel, comprising: embedding the embeddedinformation signal into at least a portion of the host signal using aninformation embedder, wherein the portion of the host signal has abandwidth smaller than the bandwidth of the host signal channel;modulating the host signal with the embedded information signal using aninformation embedding modulator, producing a composite signal comprisinginformation from both the host signal and the embedded informationsignal; transmitting the composite signal over a communication channelto the user end; receiving the composite signal at the user end; anddemodulating the composite signal using an information extractiondemodulator adapted for extracting the embedded information signal fromthe composite signal.
 119. The method of claim 118, further comprisingextracting an extracted information signal, corresponding to theembedded information signal, from the composite signal.